1. Field of the Invention
The present invention relates to a mower blade such as a mower blade that can be rotatably driven and centered around a vertically-oriented axis in an interior of a housing.
2. Description of Related Art
A mower blade generates airflow within a housing using fan blades, with the airflow causing grass to stand upright in order to facilitate cutting, transporting the cut grass, and the like. Conventionally, this type of mower blade is described in documents such as Japanese Patent Laid-open Publication No. S61-135515 and U.S. Pat. No. 4,559,769, for example. Japanese Patent Laid-open Publication No. S61-135515 and U.S. Pat. No. 4,559,769 describe a rotary mower blade as the mower blade. The mower blade of Japanese Patent Laid-open Publication No. S61-135515 includes a cutting blade formed along a long side of a plate-shaped member and a fan blade extending parallel to the cutting blade. The mower blade of U.S. Pat. No. 4,559,769 includes a cutting blade and a fan blade. At each of two apexes of the substantially rectangular plate-shaped member, the two apexes lying along a diagonal line, the mower blade includes cutting blades spanning a predetermined area beginning at the apex and following the long side of the plate-shaped member. At two apexes lying along another diagonal line, a vicinity of the apex is given a notched shape. A predetermined area including the notched portion is folded back across the adjacent long and short sides of the plate-shaped member such that the predetermined area including the notched portion stands upright, thus forming a trapezoidal fan blade.
In the mower blade disclosed in Japanese Patent Laid-open Publication No. S61-135515, the fan blade extends parallel to the cutting blade formed along the long side of the plate-shaped member. In other words, the fan blade extends parallel to a length direction of the mower blade. Therefore, airflow caused by the fan blade moves in a rotation direction (a direction tangential to a rotation trajectory of an outside end of the mower blade) or even further outward than the rotation direction. Therefore, the mower blade may not be able to generate sufficient airflow in a transport direction of the cut grass. Meanwhile, in comparison to the fan blade extending parallel to the cutting blade formed along the long side of the plate-shaped member, the configuration described above for the mower blade of U.S. Pat. No. 4,559,769 includes the fan blade facing an interior of the rotation direction of the mower blade. Airflow directed further inward than the rotation direction (the direction tangential to the rotation trajectory of the outside end of the mower blade) can thus be caused, thus generating airflow in the transport direction of the cut grass. However, in the mower blade of U.S. Pat. No. 4,559,769, a space between a lateral side of the fan blade facing a mowing chamber wall and an opposing lateral side of the fan blade decreases toward an end of a fan blade extending from a blade main body, thus creating a tapering shape to the fan blade. Thus, insufficient airflow may be generated and a desired air circulation performance may be difficult to achieve.
In view of the above circumstances, there is an urgent need for a mower blade capable of generating airflow in an appropriate direction with superior air circulation performance.